The field of the invention is the purification of butinediol-1,4 (2-butyne-1,4-diol) and the invention is particularly concerned with this purification by distilling butinediol-1,4 without danger.
The state of the art of purifying butinediol-1,4 by distillation may be ascertained by reference to the Kirk-Othmer, "Encyclopedia of Chemical Technology", Vol. 1 (1963), pages 602-609, particularly the section on Health and Safety Factors on page 607, the disclosures of which are incorporated herein.
It is known, for example from Kirk-Othmer, ibid., page 607, that butinediol-1,4 decomposes spontaneously beyond a temperature which depends on the purity of the product and this temperature can vary upward and downward. This decomposition can take place explosively. This foreseeable hazard of butinediol-1,4 requires special precautions during the necessary purifying operations, whereby the purification procedures frequently are costly in terms of the steps which must be applied.
Thus in practice purified butinediol-1,4 is obtained from the approximately 35% aqueous solution resulting from the production of butinediol. This 35% aqueous solution is treated with activated carbon and following filtration, the water is removed under vacuum at about 80.degree. to 90.degree. C. for example through the head into a falling film evaporator. The dehydrated butinediol is discharged from the sump.
As observed above, a purification of the raw product has been very risky when distillation is used.